System and method for producing and/or desalinating water using absorption refrigeration

ABSTRACT

A system and method for producing water from ambient moisture using an absorption chiller is provided. A portion of the chilled water coil is exposed to the air and the system is configured to collect and/or store for later use, water formed from atmospheric moisture condensing on this portion of the chilled water coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to co-pending Provisional Patent Application No. 61/447,929, filed on Mar. 1, 2011, entitled SYSTEM AND METHOD FOR PRODUCING WATER USING AN ABSORPTION CHILLER, that application being incorporated herein, by reference, in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to the production of potable water, and more particularly, to a system and method for producing water drawn from the atmosphere using an absorption chiller.

2. Description of the Related Art

Absorption chillers are known. For example, FIG. 1 shows a prior art absorption chiller 10 of the WFC-S series used for heating and air conditioning applications and produced by the YAZAKI CORPORATION of Tokyo, Japan. The YAZAKI CORPORATION absorption chiller 10 uses water as the refrigerant and lithium bromide as the absorbant. The cooling cycle of the YAZAKI CORPORATION device shown in FIG. 1 operates as follows. In the system of FIG. 1, water is heated to approximately 158°-203° F. by solar thermal energy or another heat source and the heated water (i.e., “heat medium”) enters the system at point “A”. Although not shown, the water recirculation of the heat medium, the cooling water and the chilled water are controlled by pumps which are provided as part of the system of FIG. 1. When the thermal transfer fluid inlet temperature of the generator section 20 exceeds 154.4° F., a solution pump provides a weak (i.e., dilute) lithium bromide solution into the generator section 20. The solution, in the presence of that heat, gives up the water as water vapor. After separation, the refrigerant water vapor flows to the condenser section 30, and a strong (i.e., concentrated) lithium bromide solution remaining in the generator section 20 is pumped to the heat exchanger 40, by the solution pump 45, where it is precooled, before flowing to the absorber 80. In the condenser 30, refrigerant vapor is condensed on the surface of the cooling coil 32, and latent heat is removed by the cooling water circulating through the condenser 30. More particularly, the cooling water absorbs the latent heat in the condenser section 30 and the heated water flows out of the condenser section 30 and into a cooling tower 60, for cooling, prior to being recirculated. Refrigerant water vapor, thus, condenses in the condenser 30 and liquid refrigerant accumulates and passes through an oriface 34 into the evaporator 50. In the evaporator 50, the refrigerant liquid is exposed to an area in a vacuum. As water flows over the surface of the evaporator coil 52, it changes states and removes heat, equivalent to the latent heat of the refrigerant (in the present case, water), from the chilled water circuit. The chilled water, which is cooled to about 45° F., is provided to a fan unit 70, shown in FIG. 1, for use in air conditioning applications. The vaporized water is attracted to the absorber section 80, which is also in the vacuum space. In the absorber 80, a deep vacuum is maintained by the affinity of the strong solution from the generator 20 with the refrigerant vapor formed in the evaporator 50. The refrigerant vapor is absorbed by the strong lithium bromide solution flowing across the surface of the absorber coil 82. The heat of condensation and dilution are removed by the cooling water and rejected to the cooling tower 60. The resulting weak solution is preheated in a heat exchanger 40 before returning to the generator 20, and the cycle is repeated.

The use of a cooling tower 60, however, contributes to the loss of the cooling water, as it evaporates in the cooling tower 60 and is lost to the atmosphere. Additionally, although used for heating and air conditioning applications, the absorption cooler 10 of FIG. 1 has not been utilized for other purposes. What is needed is an absorption chiller that does not lose cooling water to the atmosphere through evaporation from a cooling tower. What is additionally needed is a system and method for producing water from moisture in the atmosphere using an absorption chiller and/or in the production of fresh water from salt water.

SUMMARY OF THE INVENTION

A system and method for producing potable water from ambient moisture using an absorption chiller is provided.

In one particular embodiment of the invention, an absorption chiller is provided wherein the cooling water circulating through the condenser and absorber is, first, cooled to the ambient outside temperature. Subsequently, the ambient temperature cooling water is further cooled by cool air from a chilled water coil to further reduce the temperature of the cooling water. Further, the chilled water coil, instead of being exposed to an interior insulated space, is merely open to the atmosphere, causing moisture from the atmosphere to condense thereon and produce water.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a system and method for producing and/or desalinating water using an absorption chiller, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of the specific embodiment when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings in which:

FIG. 1 is a schematic diagram of an absorption chiller for air conditioning applications, as known in the prior art;

FIG. 2 is a schematic diagram of a system for producing water from atmospheric moisture using an absorption chiller in accordance with one particular embodiment of the present invention;

FIG. 3 is a schematic diagram of a combination condenser-subcooling device in accordance with one particular embodiment of the present invention; and

FIG. 4 is a schematic diagram of a system for producing water in accordance with another embodiment of the present invention.

Like reference tags and/or numerals refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 2, there is shown a system 100 for producing water from atmospheric moisture using an absorption chiller, in accordance with one particular embodiment of the instant invention. The system 100 includes, at its core, an absorption chiller similar in many respects to the absorption chiller of FIG. 1. The refrigerant in the absorption chiller of system 100 may be water, if desired, as in the absorption chiller of FIG. 1. Similarly, if desired, the absorber could be selected to be lithium bromide, as was described in connection with the absorption chiller of FIG. 1. Additionally, the generator, condenser, absorber and evaporator of the system 100 operate the same as described in connection with those same parts of the absorption chiller of FIG. 1 and, as such, the description of those parts will not be duplicated here.

However, it can be clearly seen that certain elements of the system 100 are not present in, nor contemplated by, the absorption chiller for air conditioning applications described hereinabove in connection with FIG. 1. For example, as shown more particularly in FIG. 2, the system 100 includes a heat medium source 110 that includes multiple hot water sources. In particular, during the day, hot water can be provided from the hot water heater 110 a, which can be a solar heater. At night, when a solar heater is not useful, alternate heating sources 110 b (such as gas or electric) can be used. The high temperature coolant of a water-cooled gas generator can be used, thereby providing electrical power, as well as heat utilized in the chiller-generator section. Additionally, the heat sources 110 b can also be used during the day, if desired, to supplement and/or replace the operation of the solar heat source 110 a.

Thus, in the system 100, the heat medium is provided to the generator section of the absorption chiller 10 from the heat medium sources 110 a and/or 110 b.

The system 100 of the invention has been further modified such that the cooling tower of FIG. 1 can be eliminated. This permits the cooling water to be provided in a closed system that will not lose water to evaporation, as happens in a cooling tower. More particularly, the system 100 includes an air-cooled water coil 102, which, in one particular embodiment, is placed outside, i.e., exposed to the outside ambient air. Water that has absorbed the latent heat in the condenser section 30 is output from the condenser section 30 to the air-cooled water coil 102, which reduces the water temperature to the ambient temperature. For example, if the ambient temperature to which the air-cooled water coil is exposed is an ambient outside temperature of 75°, the cooling water exiting the air-cooled water coil will be 75° or close to 75°. However, if the ambient outside temperature is warmer than the water leaving the condenser section 30, the portion of the coil 102 exposed to the outside ambient air can be bypassed using the bypass configuration 103.

As further shown in FIG. 2, subsequent to exiting the air-cooled water coil 102 or bypass 103, the cooling water of the invention is provided to a cooling water coil 120 that has been placed downstream of (and, most preferably, adjacent to) the air being forced over the chilled water coil 130 of system 100. As such, the cooling water coil 120 receives cooled air from the chilled water coil (which is at about 45° F.) and, thus, the cooling water is further cooled from the outside ambient temperature to about 55° F. This use of the cooled air from the chilled water coil 130 to cool the cooling water coil 120 is not possible when the absorption chiller 10 is used in an air conditioning application.

Additionally, as the chilled water coil 130 of system, 100 is not used in an air conditioning application, but is, instead, placed in an outdoor environment, atmospheric moisture around the chilled water coil 130 condenses on the chilled water coil 130 and is collected as water in a water collection tray 135 located beneath the chilled water coil 130. If desired, a portion 137 of a subcooling device can optionally be provided in the water collection tray 135 to further cool the water within the cooling water circuit. For example, as shown more particularly in FIG. 2, a portion 137 of the cooling water line passes through a coil in the water collection tray before passing into the cooling water coil. The water from the collection tray 135 can be provided to a water storage tank or vessel 140 for storage and/or use.

Referring now to FIGS. 2 and 3, there will be described one particular embodiment of a subcooling device 150 that can, optionally, be used in the system 100 of FIG. 2. More particularly, a subcooling device 150, including an auxiliary refrigeration unit, can be provided to even further increase the efficiency of the system 100. Upon startup, proper temperature condensing water is required. With the absence of a water tower in the embodiment of FIG. 2, only ambient temperature water is available at startup, resulting in an absence of chilled water for providing cool air to the enclosed air cooled, cooling water circuit. Therefore, a subcooling device 150 is included to provide condensing upon startup.

More particularly, as shown in FIG. 3, an auxiliary refrigeration or subcooling device 150 is provided to subcool the refrigerant (i.e., water, in the present embodiment). In the embodiment of FIG. 3, the subcooling device 150 is a combination condenser/subcooling device configured in two segments. A first segment 158 of the device 150 is located within the condenser section of absorption chiller 10′, while a second segment 156 is placed in contact with the liquid (condensed water) refrigerant that is ready to enter the evaporator section 50 of the chiller 10′. More particularly, a first portion of the evaporator coil 158 is provided in the condenser section of the chiller 10′, while another portion of the evaporator coil 156 exits the condenser and encircles the line from the condenser to the evaporator 50, above the valve 34. The subcooling device 150 is a refrigeration device, and in addition to the evaporator coil 156, 158, additionally includes a compressor 152 and a condenser 154 in fluid communication with the valve 160. Hence, by lowering the temperature of the liquid refrigerant entering the absorber section 80 of the system 100, the temperature of the liquid, when changing state within the evaporator, will be lowered proportionally.

Referring now to FIGS. 2 and 4, there will additionally be described a system for making water in accordance with another particular embodiment of the invention, in which potable water is made from salt or sea water. The performance of the system 100 can be improved by saturating the air surrounding the air-exposed chilled water coil 130. In one particular embodiment of the invention, the air surrounding the chilled water coil 130 is saturated with water evaporated from salt water. The system thus acts as a desalinator (converting salt water to potable water). Referring now to FIG. 4, there is shown a desalination device 200 for use in a system including an absorption chiller, such as the system 100 of FIG. 2. More particularly, a salt water storage tank 210 receives salt water from a salt water source via the supply line 215. A level control mechanism 217 controls the supply of salt water to the tank 210 from the supply line 215. In one particular embodiment, a float level control is used as the level control 217. Salt water from the storage tank 210 is circulated through an evaporative medium 220, using a recirculating pump 230.

The evaporative medium 220 is located proximal to, and/or, within the air flow in front of (i.e., upstream of) the chilled water coil 130 of FIG. 2. If desired, the water being circulated by the pump 230 is warmed slightly by a heating device before entering the evaporative medium 220. In one particular embodiment of the invention, the heating device 240 includes a solar water heating device or panel disposed inline between the tank 210 and the evaporative medium 220. The salt water evaporates in the evaporative medium 220 and the salt is retained in or on the evaporative medium, while a resultant humid air stream is created. Water not evaporated on the evaporative medium 220 is returned to the tank 210 by the return 225. Humidity from the humid air stream thus produced is condensed on the chilled water coil 130 to produce potable water. The evaporative medium 220 additionally acts as an air filter for the air being transported across the chilled water coil 130. Consequently, the device 200 creates a desalinated humid air stream that is converted by the chilled water coil 130 of the system 100 of FIG. 2 into potable water.

Thus, the system 100 uses absorption chiller principles to produce water from atmospheric moisture surrounding the chiller. The absorption chiller 10 operates efficiently by cooling water for the system without using a conventional water cooling tower. More particularly, water that has absorbed heat in the evaporator and/or condenser sections is first brought to ambient temperature in an air-cooled water coil and, subsequently, brought to a lower cooling water temperature (75° in the preferred embodiment) by passage through a cooling water coil placed downstream of the air blowing over the chilled water coil, thereby, cooling it. The chilled water coil, while not in use for air conditioning applications, serves both to cool the cooling water coil to provide cooled water to the system 100 and to condense atmospheric water thereon. This condensed atmospheric water can be stored and used to provide water for drinking and other uses.

The present disclosure is provided to allow practice of the invention, after the expiration of any patent granted hereon, by those skilled in the art without undue experimentation, and includes the best mode presently contemplated and the presently preferred embodiment. Nothing in this disclosure is to be taken to limit the scope of the invention, which is susceptible to numerous alterations, equivalents and substitutions without departing from the scope and spirit of the invention. 

1. A system for cooling water, comprising: an absorption chiller including a condenser section and an evaporator section; a chilled water coil including a first section of chilled water coil within said evaporator section and a second section of chilled water coil, in fluid communication with said first section, located outside of said absorption chiller; a first section of cooling water coil passing through at least said condenser section to remove latent heat from said condenser section; a second section of cooling water coil, in fluid communication with said first section of cooling water coil, said second section of cooling water coil being disposed adjacent to said second section of said chilled water coil so as to be cooled by said second section of said chilled water coil, such that water exiting said second section of cooling water coil is provided to said first section of cooling water coil at a temperature below ambient air temperature.
 2. The system of claim 1, additionally comprising a further section of cooling water coil in fluid communication with said first section of cooling water coil, said further section of cooling water coil being exposed to ambient temperature air, to cool the water in further section to ambient air temperature.
 3. The system of claim 1, further including an auxiliary cooler, a portion of said auxiliary cooler being located in said condenser section.
 4. The system of claim 1, further including an auxiliary cooler, a portion of said auxiliary cooler being placed in thermal communication with refrigerant that is about to enter said evaporator section.
 5. A method of producing water, comprising the steps of: providing the system according to claim 1; collecting water produced by moisture condensing on said chilled water coil.
 6. A system for producing water, comprising: an absorption chiller including a condenser section and an evaporator section; a chilled water coil including a first section of chilled water coil within said evaporator section and a second section of chilled water coil, in fluid communication with said first section, located outside of said absorption chiller; said second section of chilled water coil being exposed to atmospheric moisture to produce condensation in the form of water, said second section of chilled water coil being configured to permit said water to form and accumulate on said second section of chilled water coil; a first section of cooling water coil passing through at least said condenser section to remove latent heat from said condenser section; and a second section of cooling water coil, in fluid communication with said first section of cooling water coil, said second section of cooling water coil being disposed adjacent to said second section of said chilled water coil so as to be cooled by said second section of said chilled water coil, such that water exiting said second section of cooling water coil is provided to said first section of cooling water coil at a temperature below ambient air temperature.
 7. The system of claim 6, further including a collector for collecting and storing the water formed on said second section of chilled water coil.
 8. The system of claim 6, further including an auxiliary cooler, a portion of said auxiliary cooler being located in said condenser section.
 9. The system of claim 6, further including an auxiliary cooler, a portion of said auxiliary cooler being placed in thermal communication with refrigerant that is about to enter said evaporator section.
 10. The system of claim 9, additionally including a further section of cooling water coil in fluid communication with said first section of cooling water coil, said further section of cooling water coil being exposed to ambient temperature air, to cool the water exiting from said further section to ambient air temperature.
 11. The system of claim 6, further including a desalination system producing a humid air stream proximal to said chilled water coil.
 12. The system of claim 11, wherein said desalination system includes an evaporative medium for evaporating salt water circulated between a source of salt water and the evaporative medium.
 13. The system of claim 12, further including a heating device disposed between said source of salt water and said evaporative medium.
 14. A method for producing water, comprising the steps of: providing the system of claim 6; and collecting water condensing on said second section of chilled water coil in said collector.
 15. The method of claim 14, further including the step of: providing a desalination system to produce a humid air stream proximal to said chilled water coil.
 16. The method of claim 15, wherein said desalination system includes an evaporative medium, a source of salt water and a pump for pumping salt water into the evaporative medium, thus producing the humid air stream.
 17. The method of claim 16, further including the step of warming the salt water before it enters the evaporative medium.
 18. A system for producing water, comprising: an absorption chiller including a generator section, a condenser section, an absorber section and an evaporator section; a hot water coil passing between a hot water source and said generator section; a cooling water coil, at least a first portion of said cooling water coil passing through said condenser section; a chilled water coil including a first section of chilled water coil within said evaporator section and a second section of chilled water coil, in fluid communication with said first section, located outside of said absorption chiller; and said second section of chilled water coil being exposed to atmospheric moisture to produce condensation in the form of water, said second section of chilled water coil being configured to permit said water to form and accumulate on said second section of chilled water coil.
 19. The system of claim 18, wherein the hot water source includes at least one of a solar hot water heater, a gas hot water heater and an electric hot water heater.
 20. The system of claim 18, wherein another portion of said cooling water coil is provided in contact with, or immersion in, water produced by said chilled water coil.
 21. The system of claim 18, wherein water in another portion of said cooling water coil is disposed adjacent to said second section of said chilled water coil so as to be cooled by said second section of said chilled water coil, such that water exiting said second section is provided to said first section at a temperature below ambient air temperature.
 22. The system of claim 18, additionally comprising a further section of cooling water coil in fluid communication with said first portion of cooling water coil, said further section of cooling water coil being exposed to ambient temperature air, to cool the water in said further section to ambient air temperature. 